Plumber explains what radiator numbers really mean and why you should 'leave it' at 3

[ericmark]

The article continues:-

Note it says all. I still have I think 4 radiators with the *123456 marked on them, but most show ºC, and what set to, rather than room temperature. I have 3 types, Bluetooth only which only show target, Wi-Fi which show target and current, and Wi-Fi linked which can fire the boiler.

However I find the old mechanical TRV heads, have around 2ºC or more between fully closed and fully open. So 3 = 19 - 21ºC. Not as the MSN article says a fixed temperature.

They do seem to have become more expensive, my eQ-3 cost me £15 in 2019 but today . I am moving to Drayton Wiser, but they do far more to the cheap models. Yet we still see adverts like this who in their right mind would pay that much for a mechanical TRV head?

 

[Harry Bloomfield]

Yet we still see adverts like this whn their right mind would pay that much for a mechanical TRV head?

Me, I have them fitted all round. They are very reliable, don't need batteries, they just work without any fuss.

However I find the old mechanical TRV heads, have around 2ºC or more between fully closed and fully open.

You are misunderstanding, they do maintain the temperature fairly accurately, they work in an analogue fashion. As the room temperature rises, and they near their set point, they gradually close, until the hit the set point where they are fully closed, as heat is lost, they gradually open more. creating an accurate temperature. They operate, by modulating the flow, just as a modulating boiler is able to.

The digital ones, must have some built in hysteresis, but they can only be open or closed.

 

[ericmark]

The digital ones, must have some built in hysteresis, but they can only be open or closed.

Incorrect, you will hear them opening or closing a little more to maintain the radiator temperature to that required to maintain room temperature. With mothers house (modulating boiler) the radiators would just stay warm, this house a bit of a mess, as boiler does not modulate, simply on or off, but the TRV heads seem to maintain the room well, the problem room is wife's bedroom, as about the coldest room in the house, so that room has the Wiser TRV head, so it can start the central heating.

I am undecided, as to if a wall thermostat would have been better? Likely due to stuff stored around the radiator the TRV is better, as if she stops the circulation from radiator then TRV still gets hot and turns boiler off, if a wall thermostat was used, it may never turn off, as wife has so much stuff pilled around the radiator. If she does something daft so is cold, then she can correct it, but if her daft storage causes the boiler to run longer we are both poorer as a result.